The present invention relates to the technology for increasing reliability in an information processing system, and more particularly to the technology effectively applied to data protection in an information storage device configured using a nonvolatile semiconductor memory.
Information storage devices such as CF (Compact Flash) cards, smart media, memory sticks, and multimedia cards are widely known as external storage media of personal computers, multi-function terminals, and the like.
In some of these information storage devices, the reliability of read/write data is increased by calculating error positions and error correction data in a host device.
Also, some of the information storage devices increase the reliability of read/write data by providing an error detection circuit. In this case, in reading/writing of data, data required to have high reliability is subjected to an error detection circuit in correction mode, while data not required to have high reliability is not subjected to the error detection circuit (e.g., Patent Publication 1). Some of the information storage devices perform optimum error corrections by changing correction capability according to access speeds (e.g., Patent Publication 2).
[Patent Publication 1]
Japanese Unexamined Patent Publication No. Hei 4 (1992)-95299
[Patent Publication 2]
Japanese Unexamined Patent Publication No. Hei 6 (1994)-161906